1. Field of the Invention
The present invention relates to a query transformation system for transforming a query consisting of a mother language into a corresponding one consisting of a foreign language, thereby enabling users, who use only the mother language, to use a retrieval system for information consisting of a foreign language. In particular, the present invention relates to a query transformation system and method capable of not only solving an ambiguousness of words involved in the transformation of queries from one language to another language, but also executing its processing independently of the processing of an information retrieval system used, so that it can be applied to a variety of information retrieval systems, thereby enabling the information retrieval system used to function as a multilingual information retrieval system.
2. Description of the Prior Art
Recent expansion and the spread of Internet results in a rapid increase in the number of web documents on the Internet. In this connection, a variety of web document retrieval systems have been proposed to provide services for retrieving web documents associated with queries of users. Most known web document retrieval systems are used for monolingual web documents. Retrieval systems for multilingual web documents such as Altavista and Yahoo have also been proposed.
Where a retrieval system only supporting monolingual documents is used, users should input queries consisting of the same language as the language used in the retrieval system. For this reason, users, who use a language other than the language used in the retrieval system, can not utilize such a retrieval system. On the other hand, retrieval systems supporting multilingual documents have a problem in that queries should be made up using the same language as those of documents to be retrieved.
For instance, where it is desired to retrieve foreign news for a report on "airplane crash accidents" using a conventional web document retrieval system such as the Altavista, an associated English query "airplane crash accident" should be input in the case in which the document to be retrieved is made up using English language. Where the document to be retrieved consists of Korean language, a corresponding Korean query should be input. That is, the query should be made up using a language corresponding to the document to be retrieved.
Recently, home page retrieval systems, such as the Shimani, adapted to retrieve Korean documents have been proposed which support an extension to English queries. Such systems use a method for transforming Korean words into corresponding English words by simply using a Korean-English translation dictionary.
For example, in the case of a Korean query (airplane crash accident)", its words (airplane)", (crash)" and " (accident)" are transformed into corresponding English words by reference to a Korean-English translation dictionary. That is, English words "airplane", "aircraft" and "plane" are obtained for the Korean word (airplane)" from the Korean-English translation dictionary. For the Korean word (crash)", English words "fall" and "crash" are obtained. For the Korean word (accident)", English word, "thought" and "accident" are obtained. However, this query transforming method simply using a translation dictionary has a problem in that the system performance, as related to retrieval accuracy, in retrieving English documents may be greatly degraded when the resultant English query includes an ambiguous word such as the word "thought" in the above-mentioned case.